The invention relates to apparatus in which camera film or other strip material may be fed or advanced longitudinally by controlled amounts or into predetermined successive positions in processing apparatus such as film cutters, printers, markers or notchers. The invention is herein illustratively described by reference to its preferred application, namely as a positioning feed for camera film cutters, wherein the film is of the type having locating holes spaced at intervals along one edge of the film and utilized in operation of the camera to stop the film at each successive exposure frame positions. In the illustrative cutter system such locating holes are used to control actuation of the cutter blade as a function of film advance positioning.
A broad object of this invention is to devise a film strip positioning feed device recurringly operable in response to detection of successive film locating holes in such manner as to position the film accurately in the cutter or other processor regardless of distortion and damage of the locating hole edges that typically may occur with some films due to mishandling of the camera.
In some cameras the film strip is advanced into its first and succeeding exposure frame positions through manual rotation of a take-up spool until a dog in the camera drops into one of a series of locating holes along an edge of the film and thereby arrests the film against further advancement by continued application of torque to the take-up spool. Once the pawl catches the trailing edge of a locating hole, the film continues to be thus held until the camera shutter is actuated and thereby releases the pawl. Forceful attempts to advance the film further against resistance of the pawl will permanently tear or otherwise distort the film at the trailing edge of the film locating hole. Yet, persons inexperienced or careless in camera operation will evidently attempt to overcome resistance of the pawl because considerable film damage is seen in the processing laboratories. Although films sustaining such hole damage may be printable, cut and packaged if specially handled, nevertheless they present a serious problem to the processor desiring to do precision work using automated processing equipment.
Camera film of the type described is typically premounted stretched ready for use between supply and take-up reels enclosed in a light-proof plastic cassette designed for compact pocket-size cameras. In the commercial processing of such film the plastic cassette casings are broken open to remove the film, the exposed film developed, the developed film strips spliced end-to-end with others and wound on a large storage reel that feeds it through a printer. It is next advanced through a mechanized or automated cutter that typically severs it into lengths of four exposure frames each, a size that can be conveniently handled and packaged in an envelope for delivery to the customer.
The successive film strips are all similarly oriented when spliced together and wound on the storage reel. However, some processing devices are designed to accept the film with the emulsion side up and some with the emulsion side down. As a result the edge of each locating hole in the film which was a leading edge in advancing the film through the camera can become either a leading edge or a lagging edge when the film is being advanced through the processing device, depending upon the type of equipment in use. Thus locating hole edge damage presents a significant problem in locating the film precisely in the processor during film feed unless means are employed to identify and operate selectively in response only to the undamaged hole edges and to ignore or reject all other effects. Heretofore, film position feed devices attempting to work with such camera-damaged film have either not been designed in recognition of this problem or have not effectively dealt with it. As a result imprecise positioning of the film has caused an inferior product. For example, with some prior feed devices, locating hole edge damage in the film could cause a cutter to make it cut within the borders of an exposure instead of down the middle of the narrow zone between successive exposure frames as desired.
Therefore, a further object hereof is to provide film strip feed means wherein consistent reliability of film positioning through the aforesaid selective detection with reference to the undamaged locating hole edges will not be impaired by false detection signals due to jagged rents in a damaged edge falsely simulating the good edges of a succession of locating holes as sensed by the sensing means.
Still another object of this invention is to devise a camera film positioning feed and control means adapted for use with any of different commercially available film cutters or other processing devices, regardless of film orientation required therein.
A further object hereof is to devise a high-speed and reliable apparatus which itself handles the film without marring or otherwise damaging the film.